Comparisons drawn with McKinnon case over alleged attack on Department of Energy.
The US filed for extradition of a British citizen accused of hacking the American government, reopening a case that began in 2013.
Lauri Love, a 30-year-old from Suffolk, is accused of breaking into networks belonging to the Federal Reserve, Nasa and the US Army, and faces three separate criminal charges after his arrest on Wednesday.
American prosecutors believe that Love, going under the nickname "Peace", was able to attack the Department of Energy and steal the personal data of 104,000 current and former staff after gaining "unlimited access" to the systems in January 2013.
Blamed for the intrusion was an unpatched flaw in Adobe ColdFusion, a platform for developing software.
The re-arrest of Love by the Met comes more than a year and a half after the National Crime Agency first apprehended him in October 2013, seizing much of his computer equipment.
Though the alleged hacker was bailed at the time this was cancelled over a year ago, with no further action following and no demands from the US that he should be extradited.
Karen Todner, solicitor for Love, told the BBC that the re-arrest had come "out of the blue" and confirmed that he would be fighting extradition to the US.
After the recent arrest Love appeared at Westminster Magistrates’ Court, but was bailed until the start of September, where he will face further hearings.
His case will invite comparison with that of Gary McKinnon, a British computer hacker pursued by the US for a decade after he broke into US defence sites, who was also represented by Todner.
Home secretary Theresa May eventually blocked the extradition order in 2012, arguing that the risk of McKinnon’s mental health problems being exacerbated meant if she approved the order it would breach his human rights.
The extradition against Love also comes during a surge in American cybersecurity fears, the country’s Office of Personnel Management having recently lost the personal data of 21.5 million federal staff.
Love could not be reached for further comment at present.
Image source: The Pentagon